Powerheads are special water pumps designed to create internal flow inside your aquarium that replicates the natural currents and wave motion of the ocean. Creating this flow has a number of really important benefits, especially in reef tanks containing corals. The proper placement of those pumps is equally as important as choosing the right pumps when it comes to achieving sufficient internal flow in a reef tank.  

The ultimate goal is to create ample movement throughout the entire volume of water in your display, without creating high-powered streams or allowing for areas of little to no flow (dead spots). While it is true that tanks containing SPS corals do require a bit more flow compared to tanks containing soft corals and LPS, in either case, you want to get water moving in every nook and cranny of the tank. This can only be achieved with effective pump placement. 

The facts are, you will move the pumps, more than once, throughout the life of your tank. Adding corals, moving the rocks, accommodating coral growth, and adding additional pumps are a reality for reef tank owners that will affect pump placement.

Flow Pattern

Different pumps create different flow patterns and this is going to be fundamental for your pump placement. Consider this flow pattern in your aquarium and what it will take to move every inch of open space inside the tank.  Sometimes a combination of different flow patterns is the best approach. 

  • Gyre Pumps create a flat, laminar flow pattern that makes them a great choice for mounting closer to the water's surface blowing across the top of the rocks. 
  • Propeller Pumps create a wider, conical flow pattern that makes them better for mounting in the middle thirds of the aquarium, often in front of or behind the aquascape. 

Some powerheads allow you to change or adjust the flow pattern with nozzles or shroud accessories which can then dictate the best mounting location/position. Some pumps are directional meaning you can angle the flow while others are not. Consult the user manual and take the time to understand the particular flow pattern your powerheads can create.  

Substrate and Aquascape

In aquariums containing sand, too much flow that is too close to the sand will cause a sand storm and constantly rearrange your sand bed. This can be annoying because it will expose the glass bottom of your tank but also problematic as it kicks sand grains up into your pumps and filtration or worse yet, covers your corals with sand. Furthermore, the smaller the grain size of your sand, the easier it is to be kicked up and disturbed which you really should take into consideration when choosing sand for your tank.     

Your aquascape will deflect, redirect, and block water flow.  Placing a pump directly facing a large rock is typically not all that effective and will likely irritate any coral growing on that rock face. At the same time, you want to achieve flow in, around, and behind your rocks to help keep detritus and fish waste from collecting in the crevices. Smart pump placement will go a long way in ensuring you get water flowing around the aquascape without wasting the full potential of your powerheads. Creating a circular motion around your rocks is often very effective and pump placement will help you achieve this.  

Tank Dimensions

Long aquariums will typically benefit from two pumps with one pump on each end of the aquarium. In, peninsula, cube, and shallow lagoon-style tanks, placing a couple of powerheads on the back wall is a great approach. Circular and bowfront tanks pose their own set of unique challenges when it comes to flow for the simple lack of a suitable mounting surface that doesn't block the viewing panels. 

The advice here is to understand that the shape of your tank dictates the suitable mounting location of your powerheads. When building a new tank, this is an important factor to consider because the water flow is so critical to the health of your tank. 

Learn More With BRStv: BRStv Buyer's Guide To Powerheads

Where Do You Need The Most Flow?

In a reef tank, this is usually across the surfaces of the rock that contain corals so you will focus a majority of the flow in these open areas in front of the rocks. You should also consider areas that may become detritus traps like behind your aquascape; adding a small pump behind the rocks to blow out fish waste and leftover food is a common tactic. Surface movement is also important for gas exchange and if you're not getting ample surface agitation with your return pump or filtration flow, using a powerhead to increase that surface agitation is important.

As the tank matures, look for areas of low flow or where you might be collecting detritus. Have you added corals to a particular area that might benefit from the increased flow? Making these observations and moving the pumps or adding more pumps to target those areas is part of the natural evolution of your tank.  

How Many Pumps Do you Need?

It's not incredibly uncommon for reef tank owners to start with a single powerhead, then add more pumps as the corals grow and fill in the scape. This helps you to achieve the flow you need in between the growing corals and around the aquascape more effectively. While we cannot give you a definitive answer for how many pumps you will need, we can give you some recommended pump positioning that will typically yield good results. 

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Single pump position Dual pump position Four pump position